Hot-air engine



(No Model.) 6 Sheets-Sheet 1. J. J. McTIGHB.

HOT AIR ENGINE.

No. 429,281. PatentedJune 3, 1890.

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,(No Model.)

. J. J. MQTIGHE.

HOT AIR ENGINE.

Patented June 3, 1890.

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('No Model.) 6 Sheets-Sheet 5.

J. J. MoTIGHE. HOT AIR ENGINE. No. 429,281. Patented June 3, 1890.

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(No Model.) '6 Sheets-Sheet 61 J. J. MOTIG'HE. HOT AIR ENGINE.

No. 429,281. PatentedJune 3, 1890.

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JAMES J. MCTIGHE, OF PITTSBURG, PENNSYLVANIA.

HOT-AIR ENGINE.

SPECIFICATION forming part of Letters Patent No. 429,281, dated June 3, 1890.

Application filed July 23, I889- Serial No. 318,435. (No model.)

To ctZZ whom it 770661/ concern.-

Be it known that 1, JAMES J. MCTIGHE, a citizen of the United States, residing at Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented certain new and .useful Improvements in Hot-Air Engines;

and I do hereby declare the following to be a full, clear, and exact description of the invent-ion, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to a novel apparatus for transforming the potential energy of heat into motive power, whereby the energy stored in the ordinary form of fuel may be utilized under conditions of high efficiency. For a complete comprehension of the manner in which this transformation can be effected, I deem it proper to lay down some well-known principles:

First. If air at ordinary atmospheric pressure be heated,it will gain in potential energy; or, in other words, its pressure will be increased, and the rapidity of increase of pressure is in proportion to the speed of the rise in temperature. If air be first compressed and then heated, there will be not only a remarkable gain in pressure, but a large relative economy in the heat needed to increase the temperature.

Second. If the heated air be cooled, it will lose the pressure due to its former high temperature, and the rapidity of this decrease of pressure will be in direct ratio with the speed of the fall of temperature.

Third. Vapors, if heated considerably above the point of saturation, are practically subject to the same laws of expansion as air or gas.

Fourth. Air and other gases practically hold toward vapors the place of vacua-t'. 6., a given space is capable of containing a certain quantity of vapor, no matter whether it be already occupied by a gas or be a perfect vacuum.

Fifth. According to Daltons law, the amount of vapor which any certain space can receive depends solely onthe temperature which the vapor will have when it occupies said space irrespective of any gas which may already occupy the same. Avessel of the ca pacity of one cubic foot can hold only a single cubic foot of water or sand; but if avapor be heated enough the same vessel can receive and contain as much vapor as would expand intoan indefinite number of cubic feet if not prevented by the walls of the vessel. In other words, the density and tension ofa vapor depend solely on its temperature and the volume of space occupied by it.

Sixth. The capacity of air for absorbing vapor depends on the temperature of the air.

The higher the temperature the more vapor it absorbs. If the air lose heat, it deposits vapor as dew. The degree of temperature at which it deposits dew is its point of satura tioni. e., at that temperature it can hold no more vapor.

Seventh. Air in expanding against resistance occupies a greater space and falls in temperature; hence if the capacity for vapor of the increased volume do not increase in exact .inverse ratio with the loss of capacity for vapor of the air, due to the fall of temperature, some of the vapor contained in the air will be deposited as dew; hence, also, if the temperature of the air be sustained during expansion, not onlyno dew will be deposited, but the capacity for absorbing vapor will be increased.

Eighth. Vapor condensing to dew gives up its latent heat of vaporization to any bodyin contact with it.

Ninth. A liquid will have its boiling-point raised if the pressure on its surface be increased, whether such pressure be that due to its own vapor or to a superincumbent atmosphere of gas or other vapor.

Tenth. The vapor arising from a liquid has approximately the temperature of the liquid itself, and may thus serve as a carrier of heat from the liquid to a cooler body.

Eleventh. The pressure on the walls of a vessel containing air or other gas and one or more vapors is the sum of the pressure of all gaseous bodies and vapors within the vessel.

Twelfth. The compression of airor gas prod'uces heat, while the compression of a saturated vapor coincident with a reduction of its volume reduces it to the form of mist, and if continued to the form of liquid.

Thirteenth. The contact between the particles of air and an absorbed vapor is so intimate that it may practicallybe said to be a contact between the smallest particles-z'. 6., between the respective molecules.

Fourteenth. If \vhilein such molecular contact the vapor be either heated or cooled, the heating or cooling effectproduced on the air will be practically instantaneous throughout the entire mass of the air.

Fifteenth. Air is heated very readily by contact with ahot bodyof somekind, scarcely at all by radiation, and only very slowly by conduction. Consequently the heating of a body of air will reach its maximum rapidity when its every molecule is in contact with a hot body.

Sixteenth. The more minutely the heating or cooling body is divided the greater will be its heating or cooling surface. A cube containing a pound of water is about three inches each way, giving an external surface of fifty-four square inches. Divided into drops .01 of an inch in diameter it will make about fifty million drops, each having a surface of .00031116 square inch thus giving a total heating or cooling surface of about fitteen thousand seven hundred square inches or about one hundred and ten square feet.

Seventeenth. It foriiori the surface presented by the thousands of millions of molecules of a pound of water in the state of mist or vapor is enormously greater than, and, in fact, may be said to be infinite compared with that of the same water in mass.

Eighteenth. hen this mist or vapor returns to the state of liquidity, the enormous heating-surface practically vanishes.

Ninetecth. \Vater evaporates rapidly when wind blows across its surface, and of course it will evaporate very rapidly if it be cast in a minutely-divided condition, such as a tine spray into a body of air.

Twentieth. Different liquids have di tl'crent boiling points, and a mixture of two liquids may be made such that in a closed vessel one will boil and vaporize before the other, and, thus reacting by its pressure, raise the boiling-point of that other.

'lwenty-first. The cooling-surfacc of a spray of cold liquid is very much greater than when the liquid stands together as one body, and in returnin to this condition the cooling-surface practically vanishes.

'lwenty-second. The vapor that arises from any liquid below the temperature of its boiling-point is considered as a gas. It is called steam only when its pressure is equal to or above that of the superincumbent atmosphere. In other words, steam is the vapor that rises from a liquid in a condition of boiling.

Proceeding upon the foregoing principles, I have designed a new type of apparatus or engine for converting the heat energy of fuel into mechanical motion; and the invention consists in the organization of devices and the arrangement and combination of parts, substantially as hereinafter fully described, and pointed out in the claims.

In the foregoing drawings, which form part of this specification, Figure 1 is a side elevation, partly sectional, of the complete apparatus. Fig. 2 is a transverse section on line a. a of Fig. 1. Fig. 3 is a similar section on line 7) Z) of Fig. 1. Fig. 1 is a horizontal section through the cylinder automatic cut-off valve and hot-water pump. Fig. 5 is a detail, partly longitudinal section and partly side elevation, showing the relation of the cylinder and distributing-valves. Fig. 6 is an end view of same, looking from the fly-wheel end. Fig. 7 is a side elevation of the air-pump. Fig. 8 is a horizontal section of one end of the air-pump cylinder, showing the air-admission port. Fig. E) is alongitudinal vertical section of the air-pump and its air-jacket complete. Fig. 10 is a plan view of part of the air-pump. Fig. 11 is an end view of theair-pump. Fig. 12 is a longitudinal vertical section of the cold water pump and cooler. Fig. 13 is a transverse vertical section of part of the cooler, showing one of the inlets for the water from the globular heads of the cylinder.

In my pending application, Serial No. 310,631, filed May 13, 1889, I have described and claimed a method of transforming heat energy into motive power, and therefore do not herein claim any such method, as this application relates entirely to the apparatus which I have designed as being a practical form of apparatus for the purpose.

The invention being based upon the heating of a gas or vaporsuch, for instance, as airby forcing a heated liquid in the form of a spray alternately into the ends of a cylinder, and simultaneously therewith forcing a spray of cold liquid into the opposite ends of the cylinder, it is obviously essential to have as parts of the apparatus a working-cylinder of suitable form, a heating-vessel for the purpose of heating the liquid to the proper temperature, a hot pump for forcing such liquid into the cylinder, and a cold pump for forcing the condensing-spray at the same time into the opposite end of the cylinder. The apparatus may therefore be said to comprise a heater, a cooler, and interposed working-cylinder with its piston, and hotand cold pumps suitably located for the purpose of injecting the liquid into the ends of the cylinder.

The apparatus further comprises a slidevalve for the control of the amount of hot water admitted at each stroke to the cylinderheads and means for automatically adjusting such valve in accordance with the demands or exigencies of the load on the engine.

The apparatus further comprises valves and cut-offs at various points, all as hereinafter fully described, and pointed out in the claims.

011 a suitable frame 1, I mount the working-cylinder 2, having the expanded or globular heads 3 and at, respectively, the latter of which is preferably cast in one piece with the bed-plate 5 of the engine, after the manner customary in engines of the general type thus far shown. Inside the cylinder 2, I arrange the piston 6, whose rod 7 extends out through the gland 8, and is attached to the cross-head 9, which in turn is connected to the drivingrod 10 in the usual manner, and this again is connected to the crank 11 on the main shaft 12, which is carried in hearings on the bedplate 1, and also on the out-board pillow-block 13, so as to permit the use of a heavy flywheel 14, in the usual way. On one side of the cylinder 2, I arrange a pump II for hot water, and on the other side another pump 0 for cold water, and at a point out-he same side as the pump 0, in a suit-able location above the latter, I place another pump A for air. These various pumps will be constructed according to the known requirements for their particular uses, since being respectively for exceedingly hot water, cold water, and air-compression each of them will require some differences in their constructive features.

On the main shaft 12 of the engine I key or otherwise attach suitable eccentrics 15 and 16, having the respective straps 17 and 18. From the strap 17, by means of a connecting-rod, (not shown) I operate the plunger 19 of the pump II. From the strap 18, by means of the respective connecting-rods 20 and 21, I operate the plunger 22 of the airpump A and the plunger 23 of the coldwater pump 0. The connecting-rod 20 is supported at its junction with the piston-rod 24 of the air-pump by means of the rockarm 25, which is bifurcated at its lower end, and is hung from the bracket 26, bolted on the outside of the globular head 4. (See Fig. 9, wherein the piston-rod 24 is shown disconnected from the cross-head which unites it to the rod 20 of Fig. 1.) Connecting-rod 21 is joined to the piston-rod 26 of the cold-water pump 0 by means of the cross-head 27, which is fitted to move in the slides 28, whose structure is bolted to the cooler K, as shown. The air-pump A receives air at the inlets 29, which lead into the valve-chambers 30, (see Fig. 7,) inside which are the usual form of checkvalves 31, which permit the entrance of air through the ports 29 into the cylinder of the air-pump, but prevent its return to the atmosphere. The ends of the air-cylinder A communicate thence directly by means of the pipes 32 with the globular heads 3 and 4 of the working-cylinder 2. I

At a suitable level belowthat of the remainder of the apparatus I place a heater B, which is conveniently constructed in the form of the tubular boiler having the furnace F below. A pipe 33, of sufficient diameter, runs from a pointsay midway of the heater 13- upwardly to the valve-chamber 34 of the hotwater pump II. This valve-chamber is arranged between the pump and the cylinder for convenience, is cylindrical in form, and is provided with a special form of valve for the purpose of eifecting an automatic cut-01f for the hot water. Its construction and relations are as follows: The pump II is provided with extensions at both ends, forming cylindrical chambers for the two ends of the slide-valve,

and each end of the pump-cylinder H communicates directly with the two ports 35 36 and 35 36" at each end. A rod 37 passes clear through the valve-chamber 34, and at the part corresponding to the location of the ports 35 36 and 35 36 is made of larger diameter than elsewhere, and this enlarged portion is grooved on two sides, as shown at 38 in Figs. 3 and 4. Upon these enlarged and grooved portions of the rod 37 are placed the valve proper, which consists of the plain cylindrical portion 39 and the groove 40, forming a port. Opposite the ports 35 and 35', respectively, are arranged coinciding ports 41 and 42, which terminate in the spraying-nozzles 43 and 44 in the respective globular heads 3 and 4. Without now referring to the automatic action of the slide-valve 37, 38, 39, and 40, I will merely say that upon each stroke of the piston 19 of hot-water pump H a certain amount of highly-heated water is pumped into one or the other globular heads 3 and 4, according to the position of the various parts of the engine, and the spraying heads or nozzles 43 and 44 cause such body of water to be thrown in the state of a fine sprayinto either one or the other of said globular heads. The spray is prevented from striking into the cylinder proper from either end by means of the diaphragms 45,which extend from the top of the cylinder down to a point relatively near the bottom.

A suitable form for the cooler is a cast-iron cylinder K, having heads 46, between which are placed the tubes 47 after the manner of the tubular boiler, an d at each end are bolted conical ends 48, the latter forming the inlet and outlet for the supply of cold water, which then flows through pipes 47. I construct the walls of the cooler K with two ports, (marked, respectively, 49 and 50.) These communicate through the valve-chambers 51 and 52, con taining the respective check-valves 53 and 54, with the two ends of the cold-water pump, as shown in detail at Fig. 12. From the coldwater pump, immediately above the valvechambers 51 and 52, are the discharge-valve chambers 55 and 56, respectively provided with the check-valves 57 and 58, and from said valve-chambers 55 and 56 are carried the two cold-water pipes 59 and 60 to and terminating in spraying-nozzles 61 and 62, respectively, which are let into the globular heads 3 and 4.

The adjustments of the eccentrics and plungers of the hot and cold water pumps are such that hot water is forced at nozzle 43 into globular head 3 and cold water forced at nozzle 62 into globular head 4, and on the return-stroke of the piston hot water is delivered into the globular head 4 and cold water into globul'ar head 3. This alternation of action relatively of the hot and cold water sprays is kept up during the whole time the engine is in operation.

At the bottom of the two globular heads 3 and 4 are the respective waste-ports 63 and v Gl,whieh, however, do not permit the passage of anything through them to the atmosphere, as in the engine forming the subjectanatter of my invention the working-fluids are not allowed to waste, but'are kept in circulation and are used over and over. The respective globular heads and at are cast with the waste-valve chambers and 66, respective] y, and in these are arranged the oscillating valves 67, which are constructed with the projecting valve-stems (58, for mechanical operation. On each of said valvc-stems I key a crank 69, and connect the two cranks together by means of the rod 7 O, and operate the two in unison by means of the connecting-rod 71, which at one end is pivoted to an extension of the crank 60 and at the other end to an elbowerank lever 72, which is pivoted in a bracket 73, mounted on the bed-plate 1, the other arm of the lever 72 being connected by means of the link '74 to the strap 18 of the eccentric 10. The valves (37 operate as three-way cocks, each of the valve-chambers being arranged with two outlets 75 and 76, respectively. Outlet 75 of each valve-chamber is connected to a waste-pipe 7 7, which passes thence to the waste inlet-port 78 of the cooler K. The outlets 70 of the valve-chambers G5 are both connected to a pipe 79, which leads directly on a downgrade back to the heater B, delivering thereinto at a higher point than the inlet to the hot-water-supply pipe 33. The hot water is therefore taken from the heater B at a point about midway of its level, and the still heated but cooler water, which is returned to the heater ll, is delivered at a higher point, but still at such a level that it will always gravitate downwardly from the cylinder to the heater when permitted to do so by the operation of the waste-valves. Similarly the connections from the globular heads 3 and 4: through the waste-valves and waste-pipes 7 7 down to the cooler K are so arranged that the cold water which has been used in the globular heads for the purpose of cooling the air and reducing its pressure will fallback to the cooler by gravity. Thus the return of both the hot and the cold water to the heater and cooler, respectively, is cltected without the loss of any power for such purpose from the engine proper, the latter having only to pump the hot and cold water into the cylinder-heads 3 and i.

The air-pump A is designed, as stated in my other application above referred to, for the purpose of maintaining an initial pressure throughout the system. To have the matter clearly understood, it may be best to consider that the heater 3 is full of water, as also pipes 33 and 79 and also the cooler K, with its connections 51,52, and 78, are full of water, and that the rest of the system at the moment of starting contains nothing but air, there being no outlet from any of the ports to the atmosphere.

For the proper and economical working of the air-pu mp A, I prefer to surroun d it with the watcr-jackct J, having the inlet 80 and the outlet 81, and through such jacket a stream of water will be kept constantly moving while the engine is in operation. At the ends of the air-pump cylinder I arrange the ports 82 and 83, and at the ends of the waterjacket the ports 84: and S5, and in operative relation with these ports Iarrangc oscillating cocks S6 and 87, provided, respectively, with the small pockets 88 and 89. The arrange ment is such that when the pocket 88 of the valve 86 registers with the port St at one end of the water-jacket the pocket 89 of valve 87 registers with the interiorof the airpump cylinder at the other end. Both valves 86 and 87 are provided with projecting stems on which are keyed the respective cranks 90 and 91, connected together by means of the rod 02. Crank 91 is extended, and to its extension is pivoted the link 93, whose other end is pivoted on the roclcarm 25, which, as previously explained, is operated through the rod 20 by the eccentric-strap 18. By this construetion at each stroke of the piston 22 of air-pump A a small quantity of water is permitted to enter the cylinder of the air-pump, sufticient to moisten it before its entrance into the general system, thereby serving the double purpose of cooling the air to lessen the power required in compression and compensate for possible loss of aqueous vapor by leakage. The dimensions of the air-pump A will be such as on experiment will be found suilicient to maintain a constant normal pressure throughout the system. The connections and positions of various parts operated by the eccentrics in the relations of the latter will be such that when the piston of the 110twater pump is at the extreme left of its stroke the pistons ot the cold-water pump and the air-pump will be at or near the extreme right of theirstrokes. 'l.heret'ore atthe same instant that the spray of hot water is thrown into one of the globular heads of the working-cyliinler a spray of cold water will be thrown into the other globular head.

The position of the waste-valves 07 in their Ollttll'llJGlS (l5 and (56 will be as follows: When the valve (37 under globular head 3 throws the waste-port (53 into communication with pipe '77, leading to the cooler, the valve 67 under globular head i throws the wasteport 64: into communication with the heater through one of the pipes '75), and. vice versa. Valve (J7 places the waste-port G3 in communication with the cooler in'nnediatelyafter the spray of cold water has been thrown into globular head 3, having previously closed the port 63, and the other valve 67 places the waste-port (31- in communication with the heater hnmediatcly after the spray of hot water has been thrown into the globular head 4-, having previously closed the port 61, and these respective positions are reversed relatively at the time of reversal of the hot and cold sprays through their respective nozzles. Valves (57 are of such size as to completely ICC cover ports 63 and Get when reversing, so as at all times to cutoff communication between the heater and cooler.

For a proper understanding of the operation of such an engine we may assume either that the system is already charged with air under pressure or that merely atmospheric pressure exists, and that the operation of the engine is relied on for quickly bringing the pressure of the air up to the normal condition. For convenience, however, I base the following description upon the assumption that the air-pressure has been accomplished. Now supposing that the apparatus, including pumps, cylinder, heater, cooler, and connections, is so charged with air under pressure that there are twenty atmospheres behind the piston, or, say, three hundred pounds per square inch, and ten atmospheres ahead of it, or one hundred and fifty pounds, the difference-bein g due to the compression effected by the piston of the working-cylinderin reaching the end of its stroke. Assuming that the movement to be given the piston 6 is toward the right, the positions of the various parts will be as shown. Fire having been started under the heater H, the contained water can be safely raised under the above-mentioned normal pressure to a temperature of at least 350 Fahrenheit without boiling. Suppose the proportions are such that the cylinder contains one pound of air on each side of the piston, and that the pumps H and C, respectively, spray into it one pound of hot water behind the piston and one pound of cold water ahead of it at each stroke. Now, as the piston moves to the right, pump H sprays water at said temperature of 350 into globular head 3, and pump C'sprays cold water into the globular head 4. The hot-water spray heats by direct contact nearly every particle of the air behind the piston, and does so at aspeed which is very rapid. This heating of the air enables it to absorb hot vapor from the immense surface of the numberless drops of hot water at a very high rate of speed, and this vapor, being yet of about the same temperature as the hot water, assists, by its molecular contact, in making the heating of the air practically instantaneous. Now, applying the formula for common temperature of a mixture of fluids of different temperatures-viz: M S (T minus equals M S, (00 minus 1",) in which M M are the weights, S S the respective specific heats, T T the temperatures, and 0c the resultant temperature, we find, supposing the air to be at 100 Fahrenheit, thatit is instantaneously heated to a resultant temperature of 315 At this temperature the pressure of the air has increased about forty per cent. above its initial pressure, this being, as before stated, three hundred pounds, the pressure will now be four hundred and twenty pounds Der square inch. To this must be added as a working element the pressure of the vapor absorbed by such heated air, which at said common temperature of 315 is nearly one' hundred pounds per square inch, thus making a total initial pressure behind the piston of five hundred and twenty pounds per square inch. The initial effective pressure will then be the difference between this and the pressure ahead of the piston. Therefore the resultant pressure will be about five hundred and twenty minus one hundred and fifty equals three hundred and seventy pounds per square inch. Under this pressure the piston moves forward and the loss of pressure due to the loss of heat consequent on expansion as the piston moves, is, by a complex series of condensations of the vapor and re-evaporations of the same, and surrender of the latent heat of the vapor to the air, partly compensated. Atthe same time in front of the piston the cold spray is entering and cold vapor is being absorbed, and therefore the heat due to compression, as fast as generated, is abstracted from the air. The position of valves 67 remains during this time, and the hot water leaves the cylinder and returns by gravity to the heater, and similarly the cold water. leaves the other end of the cylinder and by gravity returns to the cooler. During the stroke of the piston the pressure behind it eventually decreases; but by proportioning the volume of air to the stroke the decrease of pressure may be predetermined so as not to fall below that necessary to prevent the water from boiling in the heater. By making this proportion such,for instance, as 1:2, the final pressure behind the piston will be in the case given about two hundred and sixty pounds per square inch.

Therefore the mean pressure behind the piston will be five hundred and twenty plustwo hundred and sixty divided by two equals three hundred and ninety pounds per square inch. The rate of decrease of volume in front of the piston being inversely 2:1, the final pressure will be three hundred pounds. The mean resistance ahead of the piston will therefore be one hundred and fifty plus three hundred divided by two equals two hundred and twenty-five pounds; hence the total mean effective pressure on the piston will be three hundred and ninety minus two hundred and twenty-five or one hundred and sixty-five pounds, and this pressure will in the given case result from the loss of only a few degrees of temperature from the hot water, which returns to the heater while still very hot. Conversely, the cold water ahead of the piston is heated only a few degrees, gaining even less than the hot water loses, the difference being spent in useful work. On completion of the stroke the pumps H and G and cooks 67 are reversed from the main shaft by the eccentrics, so that the hot spray is now thrown into globular head 4 and the cold spray into globular head 3. Instantaneously the pressure to the left falls to one hundred and fifty pounds per square inch, and for the stroke again the mean effective pressure is as above shown. The remaining hot water now returns to the heater through the cook 67 under head 4, as before, and the cold water returns to the cooler through cock (37 under head 3, as before, and this return of the hot and cold water to their respective reservoirs or supplypoints is invariably effected by gravity. Economy is thus secured by the small amount of fuel required to heat water through a differential temperature of 35", instead of, as is usual in steam-engines, wasting nine hundred and sixty-six heat units per pound of water before the working-fluid can be obtained at all. Economy is also secured by the small amount of running water around the cooler required to abstract the small amount of heat imparted to the cold spray by the hot air and vapor. It is to be noted that the air has the hot water sprayed into it when the air itself is at its point of maximum density, and it is further to be noted that since the working body of airis confined within the cylinder on each side of the piston when the spray of hot water is pumped into the globular head the entire body of air which is to be heated becomes heated at oncei. a, at constant volume.

Instead of water, other-liquids may be used in the heater, and other gases may be used instead ofair; or two liquids of different boili ngpoints, one of which is by the high heat of the other to be first turned into the working'fluid, may be adopted without departing from the spirit of my invention.

Obviously the operation of the enginemay require a means for preventing excessive accumulation of condensed "apor in the cooler. This can be done by a pump or other device, which takes the excess accumulating and returns it to the heater, as required. Simple means foraecomplishing this end is shown at Fig. 5. Each of the waste-valves (57 has on its periphery a pocket 9i, which in the oscillation already described swings alternately into communication with the cooler-connection and 77 and with the heater-eonnection 76 and 79. Should the cooler tend to become too full of water, a small quantity will enter the pocket 9i at each oscillation and be carried by the valve over to the port 76, from which the water so carried will run by gravity down to the heater, thus keeping up the normal condition of things without having an excess accumulation in any part of the system.

Vhen the engine is in operation, automatic regulation is effected by means of the slidevalve (shown at Fig. l) interposed between the hot-water pump and the nozzles elf and t4, respectively arranged for the delivery of the hot-water spray into the two globular heads 3 and 4- of the working-cylinder. The piston-rod 37 of this automatic slide-valve is connected by suitable connecting-rod to any of the well-known forms of shaft-governors now in use. As the construction and operation of these shaft-governors are well understood to those skilled in the art to which this invention belongs, I do not describe the same further than to say that from the eccentric of such shaft-governor a connecting-rod reaches to and controls the slide-valve stem 37. It will be observed that at each end of the valve the inner edges of the gooves 40 act as cutoffs when they strike the outer edges of the ports 35 and 35, respectively, and at intermediate points they act as valves, regulating the amount of water which can flow to the spray-nozzles in agiven time. The system is such that when the engine is running at proper speed and full load the slide-valve op crates to admita full supply of hot water at each stroke. \Vhen the engine is running without any load further than that of its own friction and inertia, the shaft-governor will shorten the stroke of the slide-valve to such extent as to admit just enough hot water at each stroke to generate enough air-pressure to keep the piston (5 up to its work for the aforesaid purpose, and between these limits the shaft-govcrnor will regulate the amount of water admitted by meansof the slide-valve to the proper and proportionate extent, thereby making the engine, as awhole, strictly'autoniatic in its regulation. Inspection will disclose the fact that before the edge of groove 40 can cut off the supply of water from the port 4-2 the port will be in open communication with the cylinder 34 and heater-connection 33, since the rear of valve 39 will always reach port 30 or 36 before the cutoff occurs. This action is effected by simply making the ports 36 3o wider than ports 35 35. The result is that when cut-olf occurs earlier than normal the excess delivery of the pump II is diverted back into cylinder 34 and water-hammer is avoided. The grooves 38 allow free movement of the valve by permitting free access of the water to the end chambers beyond the valves Once the initial air-pressure is obtained the further use of an air-pump is merely necessary for the purpose of compensating for any leakage which may take place at the joints or other parts of the apparatus, and for this purpose a comparatively small pump will be sufficient.

I do not herein lay claim to the method of transforming the energy from the fuel into motive power, as such forms the subject-matter of my previously-filed application, Serial No. 310,631.

In using the expression liquid throughout this specification I desire to be understood as including not merely ordinary liquids-such as water, various kinds of oil, &c.sinee in some cases it will be found that the purpose of the invention can be accomplished by using the heater for the purpose of therein melting various normally solid substances, whether the same be in the form of metals or otherwise. In such modifications it will be necessary to take the precaution to substitute instead of air a gas of such ITO character as would not abstract energy from the cooling-surface in front of the piston are both at a maximum, at the end of the stroke both are at a minimum orhave vanished, and between these two limits both decrease in extent. This reduction of surface takes place in a way which does not detract from the economic efficiency of the conversion, but rather assistsit, since the reduction of surface takes place just in proportion to the decreasing need of heat and cold, and, considering only the space 011 one side of the piston during an entire stroke the hot surface gradually reduces and finally vanishes the instant it meets the cold spray whose surface is then at its maximum, and this in turn reduces and vanishes in the presence of the next succeeding hot spray.

The size of the engine in its practical development will be extremely small for a given power, and since onlya few gallons of water will be needed in the heater a very small amount of fuel will be required for a comparatively large output in mechanical power. For the same reason the heater will be exceedingly small compared to the size of the steamboiler required for the generation of steam to drive a steam-engine of equal power.

In the operation of my above-described type of engine there is no escape of any of the working-fluid, as the cycle of operations is continuous, and no waste occurs except that which may accidentally occur by leakage, and that due to radiation, which latter can of course be considerably reduced by properly jacketing the parts subject to such loss.

The water in the boiler is used over and and over continuously without suffering any loss in volume, and the water in the cooler is similarly used over and over continuously.

The operation of the heater in connection with the cylinder and its piston may be likened to an electric circuit, the heater representing the generator, the outgoing and returning pipes representing the circuit, and the cylinder representing the electrical trans lating device, which consumes the electrical energy at a given point in the circuit.

The application of the fuel to the heater raises the potential energy in the'circuit and this falls at the Working-cylinder in imparting its energy to the piston.

If desired, a safety-valve may be applied to the heater, so as to open outwardly if the internal pressure should exceed a predetermined maximum.

A temperature indicatorsuch, for instance, as a thermometer-may be attached to the heater for the purpose of indicating the temperature of the liquid contained there in. Likewise gage-cocks or a water-gage of approved form may be arranged on the heater.

I claim as my invention 1. In a hot-airengine, the combination, with the working-cylinder, of a chamber com municating therewith and containing the working body of air and a pump for projecting into such working body of air a spray of heated liquid.

2. In ahot-airengine, theeombination, with the working-cylinder, of a chamber in direct open communication therewith and containing the working body of air and a pump for projecting into such working body of air a spray of heated liquid.

3. In a hot air engine, the combination, with the working-cylinder, of a chamber communicating with one end thereof and containing the working body of air, a pump for projecting heated liquid into such body of air, and a pump for projecting cold liquid into the body of air after its expansion.

4:. In a hot-air engine, the combination, with the workingcylinder, of a chamber in direct open communication with one end thereof and containing the working body of air, a pump for projecting heated liquid into such body of air, and a pump for projecting cold liquid into the body of air after its expansion.

5. In a hot-air engine, the combination, with the working-cylinder, of two chambers respectively communicating with opposite ends of said cylinder, with a piston interposed between them, a pump for projecting hot liquid into the body of air in one chamber, anda pump for simultaneously projecting a cold liquid into the body of air in the other chamher.

6. In a hot-air engine, the combination, with the working-cylinder, of two chambers respectively in direct open communication with opposite ends of said cylinder, with a piston interposed between them, a pump for projecting a hot liquid into the body of air in one chamber, and a pump for simultaneously projecting a cold liquid into the body of air in the other chamber.

'7. In a hot-air engine, the combination, with the working-cylinde'r, of two chambers respectively communicating with opposite ends of said cylinder, with a piston interposed between them, two pumps for simultaneously projecting hot and cold liquid, respectively, into said chambers, and means for reversing the introduction of the hot and cold liquid relatively into said chambers.

S. In ahot-air engine, the combination,with the working-cylimler, of two chambers respect ively in direct open communication with opposite ends of said cylinder, with a piston interposed between them, two pumps for simultaneouslyprojecting hot and cold liquid, respectively, into said chambers, and means for reversing the introduction of the hot and cold liquid relatively into said chambers.

9. In a hot-air engine wherein the working body of air is alternately heated and cooled by the admission into the engine of hot and cold liquid from suitable heating and cooling receptacles, the combination therewith of; a waste-port and a movable three-way wastevalve, connections from the valve-ports to the said receptacles, and mechanical connections from said valve to the engine-shaft, arranged and adapted to connect the waste-port alternately to the heating and cooling receptacles.

10. In a hot-airengine whereinthc working body of air is alternately heated and cooled by the admission into the engine of hot and cold liquid from suitable heating and cooling receptacles at a lower level, the combination therewith of a waste-port and a movable three-way waste-valve, connections from the valve'ports to the said receptacles, and mechanical connections from said valve to the engine-shaft,arranged and adapted to connect the waste-port alternately to the heating-and cooling receptacles.

11. In a hot-air engine wherein the working body of air is alternately heated and cooled by the admission into the engine of hot and cold liquid from suitable heating and cooling recep acles, the combination, with said receptacles and the cylinder, of an interposed valve operatively connected to the engine-shaft and adapted to prevent communication between the heating and cooling receptacles or their connections, while permitting either to be brought into communication with the cylinder.

19. In a hot-airengine wherein the working body of air is alternately heated and cooled by the admission into the engine of hot and cold liquid from suitable heating and cooling receptacles at a lower level, the combination, with said receptacles and the cylinder, of an interposed valve operatively connected to the engine-shaft and adapted to prevent communication between the heating and cooling receptacles or their connections, while permitting either to be brought into communication with the cylinder.

13. In the hot-air engine wherein the working body of air is alternately heated and cooled by the admission into the engine of hot and cold liquid from suitable heating and cooling receptacles, the combination, with said receptacles, of an interposed movable valve operativel y connected to the engineshaft and having a pocket arranged f or alternate communication with said heating and cooling receptacles, whereby the undue displacement of the liquid in either receptacle is automatically corrected.

14.. In a hot-air engine wherein the working body of air is alternately heated and cooled by the admission into the engine of hot and cold liquid from suitable hcatingand cooling receptacles at a lower level, the combination, with said receptacles, of an interposed movable valve operatively connected to the engine-shaft and having a pocket arranged for alternate communication with said heating and cooling receptacles,whereby the undue displacementof thcliquid in either receptacle is automatically corrected.

15. In a hot-air engine in which the working body of air is heated by the introduction of a heated liquid, the combination, with such engine, of a variable cut-off valve interposed between the source of heated liquid and the engine and adapted to vary the quantity of liquid ad mittcd,-and a governor controlling the movement of said valve and operatively connected to the shaft of the engine.

16. In a hot'aircngine in which the working body of air is heated by the introduction of a heated liquid,thc combination, with such engine, of: a deviee-such as a pump-for projecting toward the engine uniform quantities ot heated liquid, a variable cut-off: valve interposed between the pump and the engine, means for effecting variable movement of such valve with reference to the admissionport, and a bypass arranged to divert back to the heating-receptacle that portion of liquid which may be prevented by the said valve from entering the engine.

17. In a hot-air engine adapted to have the working body of air changed in tem peratu re by the introduction of a quantity of liquid into the engine, the combination, with the said engine, of an exterior receptacle for the supply of liquid located at a lower level than the engine and means for placing the engineand said receptacle in communication at proper intervals, whereby the liquid after use returns to its receptacle by gravity and the use of a pump is avoided.

18. In a hot-air engine wherein of two working bodies of air or vapor on opposite sides of the piston one is cooled by a spray of cold liquid and the other heated by a spray of hot liquid, the combination, with such engine, of means for introducing said hot and cold sprays.

it). In a hot-air engine, the combination of the werkii'ig-cylinder, a chamber communicating therewith and containing the working body of air or vapor, a spraying-nozzle adapted to deliver a spray of liquid into such chamber, and means for forcing a liquid through such nozzle.

20. In a heat-engine wherein the pressure of the working-fluid is reduced by a jet or spray of cold liquid introduced therein, the

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combination, with such jet-cooler, of a sur- I11 testimony whereof I affix my signature in IO face-cooler arranged to cool the liquid used presence of two Witnesses. in the jet or spray.

21. In a hot-air engine, the combination, JAMES J. MOTIGHE. with theworking-cylinder, of a chamber communicating therewith and containing the \Virnesses: workingbodyof air, aspraying-nozzie adapted '1. J. MOTIGHE, to sprayhot liquid thereinto, and a heater for VICTOR E. BURKE. heating such liquid. 

